Document wxWindow InheritsBackgroundColour() and UseBgCol() methods.

These functions were present in the interface header but didn't have their own
documentation and somehow inherited the documentation of the first function in
the same section which didn't make any sense for them. Do document them now.

Closes #14607.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@72439 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

interface/wx/window.h

@@ -1923,7 +1923,16 @@ public:
     */
     void SetOwnBackgroundColour(const wxColour& colour);
 
+    /**
+        Return @true if this window inherits the background colour from its parent.
+
+        @see SetOwnBackgroundColour(), InheritAttributes()
+    */
     bool InheritsBackgroundColour() const;
+
+    /**
+        Return @true if a background colour has been set for this window.
+    */
     bool UseBgCol() const;
 
     /**